Nghiên cứu khoa học: Ngủ càng nhiều càng giàu

US President Barack Obama yawns as he attends an East Asian Summit Plenary Session at the Peace Palace in Phnom Penh on November 20, 2012. During the two-day East Asia Summit, Obama was scheduled to hold talks with the leaders of the 10-member Association of Southeast Asian Nations (ASEAN) along with Chinese Premier Wen Jiabao and Japan’s Premier Yoshihiko Noda. AFP PHOTO Jewel Samad (Photo credit should read JEWEL SAMAD/AFP/Getty Images)